This invention relates generally to a discrete particle counter and, more particularly, to a seed monitor for counting the flow of seeds dispensed by an air seeding system through a plurality of primary seed tubes and secondary seed tubes, where the seed monitor includes an optical sensor attached to one or more of the seed tubes.
As is well understood, it is important to monitor the quantity of seeds that are being planted into a planting row, especially in a high capacity agricultural environment such as a farm where the seeds are corn seeds, soy bean seeds and the like. Planting too many seeds causes the resulting plant product to be too closely spaced together to allow for proper plant growth, thus affecting the crop yield. Planting too few seeds reduces the effective use of the planting area. For high output planting, industrial seed planters have been devised to plant a high volume of seeds relatively quickly. To ensure that the proper number of seeds are planted by the seed planters, a seed monitoring system is generally provided that counts the seeds as they are dispensed through seed tubes associated with the planter. A typical seed planter will have many seed tubes for planting a multitude of planting rows simultaneously.
One type of seed monitoring system incorporates optical devices that generate an optical beam directed across the seed tubes, and optical sensors that are sensitive to the loss of light intensity caused by seeds interfering with the optical beam. An electrical counting circuit monitors the occurrences of loss of light intensity to provide a count of the seeds. Various optical seed monitoring systems of this type are disclosed in U.S. Pat. No. 3,974,377 issued to Steffen; U.S. Pat. No. 4,555,624 issued to Steffen et al.; and U.S. Pat. No. 4,163,507 issued to Bell.
These, as well as other, optical seed monitoring systems have been inaccurate for various reasons. One inaccuracy results from the spatial nonuniformity of the optical beam that senses the seeds. Because of spatial nonuniformity, the intensity of optical rays generated by the optical devices vary, depending upon the location within the optical beam. Therefore, the ability of the optical sensor to detect the interruption of the optical beam by the seeds varies depending on the location of the seeds within the beam. Consequently, the optical sensor may not adequately detect seeds being dropped through certain locations in the seed chute.
One prior art seed monitoring system has attempted to address spatial nonuniformity of the optical beam of a seed sensor by proposing an optical device that generates a trapezoidal cross-section of an optical beam. However, the trapezoidal cross-section creates an undesirable spatial restriction for groups of seeds as they are dropped through the seed tube. U.S. Pat. No. 4,634,855 issued to Friend et al. also discloses an attempt to create an optical beam of high uniformity. However, this proposed solution is of such complexity that the feasibility for commercial success is limited.
Another drawback of the known optical seed monitoring systems is attributable to the environment in which the optical sensors are operating. Because the seed planters encounter dirt, dust and various chemicals during the planting process that may accumulate in the seed tubes, the sensors may be adversely affected because of contamination of the optical components. This situation is further exasperated in those types of optical sensors in which the optoelectronic components and/or electronic circuits of the sensor are located at, or attached to, the seed tubes. Other problems arise by attempting to protect the circuits and associated wire harness connectors from the corrosive effects due to a combination of moisture and other environmental elements.
Another drawback of the known optical seed monitoring systems occurs when the seed sensors are associated with circuitry that counts pulses when the optical beam is interrupted by the seeds. This may result in a count inaccuracy because a plurality of seeds may simultaneously traverse the optical beam and be counted as a single seed. A related problem is that the accuracy of the known optical seed monitoring systems tend to deteriorate with increasing planting speed, with higher seed populations per acre, and with small grains and seeds. These optical systems may be incapable of a sufficiently rapid response to reliably count each seed.
Another type of high volume seed planter, generally referred to as an air seeding system, is also used to dispense seeds. Typical air seeding systems include a tank or hopper that holds a quantity of seeds, fertilizer, herbicides or other appropriate particulate material that is to be evenly dispensed over a field area. A series of primary seed supply tubes are connected to the hopper through a seed metering system, and a series of secondary seed supply tubes are connected to the primary tubes through a manifold to deliver the seeds to desirable locations on the seeding system where they can be dispensed into the ground. A fan forces air through the supply tubes to provide the mechanism for delivering the seeds from the hopper to the dispensing location.
The air seeding system offers a number of advantages over the traditional seed planting system. For example, air seeding systems generally have a higher productivity in that the system allows many more rows to be simultaneously planted than the traditional seed planting system.
Therefore, more acreage can be seeded at a much faster rate. Additionally, the air seeding system has a high ground clearance so that the ground does not need to be tilled or plowed prior to being planted by the air seeding system, as was necessary with the conventional seed planter. This eliminates labor, and reduces the affects of wind and water erosion.
A number of problems can occur with air seeding systems that prevent them from dispensing the seeds in a desirable manner. For example, the seed supply tubes can become disconnected, thus preventing seeds from being dispensed through the tubes. Additionally, seeds may collect within the supply tubes and cause a partial or complete blockage of the tubes, also affecting the flow of seeds through the tubes. Also, soil can enter the seed tubes at a point where the seeds are dispensed into the ground, which may cause the seed tubes to become blocked and thus prevent the appropriate number of seeds from being dispensed.
Currently available seed planter monitoring systems could be adapted for use in the known air seeding systems to monitor seed flow. However, due to such a high number of seed tubes in the air seeding system as compared with the conventional seed planter systems, this solution is generally too costly. Also, air seeding systems tend to generate more static electricity than prior art planter systems, resulting from the movement of a high number of seeds through plastic components such as air tubes at a relatively high velocity. The resulting build-up of charge can result in discharges that can readily damage sensitive electrical components of the seed monitoring system. The present invention achieves high immunity to damage from static discharge by positioning the sensitive electrical components in an environment remote from the seed tube as well as remote from the seed sensing area.
Further, conventional seed monitoring systems would be limited to being used in the secondary seed tubes, and would not be applicable to being used in the primary seed tubes. This is because the larger cross-section of the primary seed tubes cannot be adequately covered with the existing seed sensor technology available for seed planters. Therefore, it is common practice in the industry to equip only a small number of the secondary seed tubes with seed planter type sensors, which leaves a majority of seed tubes without a mechanism for monitoring seed flow.
U.S. Pat. No. 5,177,470 issued to Repas discloses a sensor device for detecting the flow of particles in an air stream that has particular use for detecting seeds in an air seeding system. This patent discloses use of a piezoelectric sensor that extends into the seed tubes. The sensor produces high frequency signals when struck by seeds flowing through the seed tubes that give an indication of the flow of seeds through the tube. A calibration system is included so that, if the seed tube becomes blocked or partially blocked, the sensor will give an indication of this blockage in a relatively short period of time.
Although different seed monitoring systems are available for monitoring seed flow in an air seeder, there is a wide area for improvements in these monitoring systems that will allow the monitoring of seed flow, including seed counting, through all of the secondary seed tubes in a cost effective manner. Further, no prior art air seeding system has attempted to monitor seed flow and count seeds at the primary seed tubes of the air seeder. It is therefore an object of the present invention to provide such an air seeder monitoring system that counts seeds and monitors seed flow at the primary and/or secondary seed tubes of an air seeder.